The present invention relates to intake manifolds for internal combustion engines; more particularly, to such manifolds formed of a polymer; and most particularly, to an intake manifold module formed by vibration welding of a plurality of injection-molded components.
An internal combustion engine, powered by either diesel fuel or gasoline, includes generally an intake manifold assembly for collecting air from outside the engine and distributing the collected air to each of the combustion cylinders. In modern engines, the manifold typically is part of a relatively complex assembly known generally in the art as an integrated air/fuel module (IAFM). The IAFM may include a variety of sub-systems for performing a host of related functions, including, for example, a throttle body and valve for air flow control, a helmholz resonator for noise suppression, an exhaust gas recirculation valve for mixing exhaust gas into the fresh air stream, a fuel rail and fuel injectors for injecting fuel to the cylinders, and a purge valve for stripping fuel from a fuel tank cannister.
Historically, intake manifolds were formed of metal such as cast iron or aluminum by molding around a sand-cast core, a costly manufacturing technique wherein the integrity of the core was destroyed by the heat of the molten metal, allowing the sand to be poured from the interior of the cooled component. More recently, intake modules are known in the art to be formed of high-temperature thermoplastic composites such as glass-filled nylon or glass-filled polyphthalamide by xe2x80x9clost corexe2x80x9d molding, a technique related to sand casting wherein a sacrificial internal core, formed typically of a tin/bismuth alloy having a relatively low melting temperature, is destroyed after the molding process.
It is highly desirable to form an intake module by less-expensive forming techniques such as injection molding, wherein a component is formed by filling a cavity between an inner and an outer mold. The shape of the component must be such that the inner mold can be released and extracted from the part upon solidification of the molding material, a requirement that heretofore has generally dictated use of a sacrificial inner mold.
Recently, it is known in the art to form an intake module for an in-line engine by injection molding matable components which may be assembled as by welding to form a finished module. However, injection molding has not been available heretofore for the formation of a satisfactory IAFM for a V-style engine because of 1) very tight tolerances required in bridging across the valley between the left- and right-bank cylinder heads, and 2) great difficulty in reliably welding mating surfaces of components within the module.
Further, in known intake manifolds, the runners carrying air from a central plenum to the individual cylinders may differ in length and/or geometry, which is undesirable because the various cylinders may experience differing air/fuel ratios. It is preferred that the runners be identical, so that each cylinder is supplied identically with air.
Therefore, there is a strong need for an improved integrated air/fuel module for a V-style engine wherein the intake manifold may be assembled from injection molded components.
It is a principal object of this invention to provide an improved intake manifold formed of components which may be readily molded by injection molding and assembled by friction welding.
It is a further object of this invention to provide an improved intake manifold wherein the air flow paths between a plenum and the individual cylinders are identical.
It is a still further object of this invention to provide an improved intake manifold formed of welded components wherein the weld integrity of each air flow runner may be readily tested.
It is a still further object of this invention to provide an improved intake manifold having superior mechanical rigidity for installation as a bridge across the heads of a V-style engine.
Briefly described, the present invention is directed to an improved air intake manifold for a V-style internal combustion engine. The manifold is assembled from three individual injection molded sections by friction welding of mating surfaces. Preferably, each section is formed of a high-melting temperature composite polymer, such as glass-filled nylon or glass-filled polyphthalamide. The mating surfaces are all on the exterior of the manifold and are so formed as to be directly accessible to welding apparatus, including clamping devices. Further, the mating surfaces are so oriented that friction welding may be carried out by relative motion between the components in the axial direction. When joined, the lower and middle sections form the individual distribution runners from the plenum to the intake ports in the engine heads. The lower and middle sections are so configured that each such runner crosses the valley of the engine, providing great strength and rigidity to the module. Further, all runners are identical, so that air flows from the plenum to the individual cylinders are substantially identical. Preferably, the middle and upper sections are rotationally symmetrical about a vertical axis orthogonal to the longitudinal axis of the module, such that each may be added to the module during assembly in either of two orientations 180xc2x0 apart, making mis-orientation impossible. Modifications may be made to any of the sections, as may be required for example to adapt the manifold to a specific engine IAFM requirement, without requiring retooling of molds for the other two sections, provided the configurations of the mating surfaces are unchanged.